Alkaline detergent composition



Patented Mar. 23, 1954 2,673,186 ALKALINE DETERGENT COMPOSITION CharlesE. Wheelock, Cincinnati, Ohio, and William B. Reynolds, Bartlesville,Okla., assignors to The Procter and Gamble Company, Ivorydale, Ohio, acorporation of Ohio No Drawing. Application January 15, 1948, Serial No.2,543

4 Claims. 1

This invention relates to detergent products having alkaline reactionand containing whitening (or color brightening) agents of a fluorescentnature.

Coumarin derivatives, particularly beta methyl umbelliferone l-methyl 7hydroxycoumarin) have found a variety of uses which take advantage oftheir abilities to absorb ultraviolet radiations and to emit fluorescentradiations in the blue end of the visible spectrum, and which are inpart dependent also on the color-free character of many of thesederivatives when viewed in visible light which is free from ultravioletradiations. Such compounds are used, for instance, as ultravioletfilters in photography, in suntan lotions, and in transparent wrappersfor perish able foods, as optical bleaches to improve the whiteness ofpaper and textiles, as whitening agents in cit-white soaps and othersubstances, and as color brightening agents in a variety of products.

The present invention is concerned with the incorporation of a selectedgroup of coumarin derivatives as Whitening or brightening agents incompositions having at least a mildly alkaline nature, and particularlyin substances of this character which are processed-after the additionof the fluorescent material-at elevated temperatures. Among suchcompositions are ordinary soaps (alkali metal salts of the higher fattyacids), washing compounds containing such soaps, and washing compoundscontaining both synthetic organic detergents and alkaline inorganicsalts such as alkaline phosphates, polyphosphates, carbonates,silicates, and borates. The manufacture of detergent compositions ofthis character frequently includes mixing and/or otherwise processingthe ingredients While in molten condition at temperatures which mayrange from about 140 F. to as high as 450 F., sometimes in the presenceof small amounts of free sodium hydroxide which is, as a rule,subsequently neutralized.

The term synthetic organic detergent, as used herein, includes withinits meaning all of the non-soap anionic detergents which arecharacterized by their high solubility in water, their resistance toprecipitation by the constituents of hard water, and their surfaceactive and effective detergent properties, such as water-soluble saltsof sulfuric and phosphoric reaction products of alkyl and substitutedalkyl compounds containing from 8 to 18 carbon atoms in the alkyl group;and all of the non-ionic detergents which are similarly characterized byhigh solubility in fill water, resistance to precipitation by the constituents of hard water, and surface active and effective detergentproperties, such as the reaction products of higher alcohols and higherfatty acids with considerable amounts of alkylene oxides. Numerousexamples of such detergents are mentioned in Linds U. S. Patent No.2,396.27 8.

The nature of the soap or synthetic detergent employed in making thecompositions of the present invention is not critical insofar asconcerns compatibility with the alkali-stable class of coumarins definedherein. These coumarins are compatible with any and all known soaps andsynthetic organic detergents-whether anionic, non-ionic, or cationic-andmay advantageously be used to whiten all such detergents. Theoutstanding benefits of the invention are however realized, as willappear, in detergent compositions of an alkaline nature, and in theformulation of such compositions one tends to avoid using detergentswhich lack alkali stability, such as some or the cationic detergentswhich are hydrochlorides.

Beta methyl umbelliferone and the other coumarin derivatives which haveheretofore been recommended as whitening or brightening agents areunstable in alkaline media, particularly at elevated temperatures, andtheir use in soaps and other detergent compositions of an alkalinenature is therefore greatly restricted. Some soaps are processed atcomparatively low temperatures during andafter the step of incorporatingminor ingredients such as perfumes, preservatives, coloring matter, andfluorescent whitening or brightening agents, and in these soaps sunlightor when packing scrap is remelted, be-

cause the decomposition products produced by the attack of alkali onunstable fluorescent materials such as beta methyl umbelliferone arefrequently highly colored compounds.

Objects of the invention are to provide soaps, soap compositions, andalkaline soap and/ or synthetic detergent compositions generally, whichhave been whitened or brightened by the incorporation of alkali-stableblue fiuorescing compounds, and which will not lose appreciablefluorescence with age, or discolor in sunlight or upon remelting.

Another object of the invention is to provide heat processed detergentsof alkaline reaction which are whitened or brightened by the incor- 3poration of fluorescent coumarin derivatives which are stable toalkalies under severe processing conditions.

Another object is to provide soap bars, granules, and flakes, andsimilar solid form products made from synthetic. detergentsin'conjunction with alkaline materials, having improved whiteness byvirtue of the incorporation of heat-stable and alkali-stable normallycolorless compounds which in sunlight fluoresce in' the blue end of thespectrum. 7

Another object is to providezdetergent.compositions (including soapsprocessed-atlow temperatures) of more permanent whiteness, due to theinclusion of blue fluorescing substanceswhich do not gradually lose thisfluorescence in mildly alkaline media at ordinary temperatures, andparticularly upon prolonged exposure to sunlight.

The general terms blue-fluorescing, or fluorescing in.;the blueiendofthe spectrum,;unless specifically applied to someone chemical compound,are used herein to'designate fluorescencein the violet-blue-greenregion. of the visible spectrum.

:Theessential whitening .(or. brightening) agent of theuwhitened (or.brightened). .detergent compositions of our invention is' a. coumarinderivativehavingthe general formula 'in whichR is an alkyl or aralkylgroup having a saturated carbon atom adjacent to the coumarin ring andcontaining no more than 15 carbon atoms,"R is hydroxy, amino, monoordi'alkylamino, monoordialkylolamino, or heterocyclic amino, and,R'iseither alkyl or hydrogen, the

number. of carbon atoms in each of said R and R groups in no caseexceeding 6.

"Representative of this class of alkali-stable blue fluorescingcompounds, all members of which are suitable for use inthe invention,are:

Compounds. of this general class differ from the more commoncoumarin-type whitening agents chiefly in the inclusion of the R group.For maximumalkali-stability we prefer to employ a comparatively .largeand/or branched R. group,

.such as benzyl and isopropyl. Although we do not wish to be bound byanytheory, it is our opinionthat compounds which lack the R group in the3 positiomwhen using the following sys- ..tem of numbering 4 lack alkalistability because of the susceptibility of the unprotected lactongrouping to-attack by alkali, whereas the presence of the R group in aprotective position appears effectively to hinder such attack. At anyrate, other- ;.wise.;.similar. compounds differ remarkably in thepermanence of their characteristic fluorescent behavion depending onwhether or not they convtain'this R group. This is illustrated by thefollowing typical ,data, measured under carefully standardized testconditions.

*Thestarred compounds are representative of those used nmcth'einvention.

It will be appreci'atedfthatthe above tests, which indicate thestability of the fluorescence in a saturated alcoholic solution ofcaustic potash, are much more drastic than any conditions met in'themanufacture of commercial detergent products. Comparisons under morepractical conditions are given in connection with following specificexamples, of the invention.

'Emamplc 1 v(a) To aquantity of molten .kettlevsoap at. a temperature.of. about 200$ F.the. soap being sodiumsoap of the: fattyaacids ofIcoconutoil and tallow of good quality-rwas added. with-.stirring.0.002% byweight of 4-methyl-7-hydroxy- .-coumarin .(beta methylumbellifer.one,,an alkaliunstable blue fluorescer). dissolved in-about..10 .times its weight of-.essential oils perfume. vA

small sample ofthesoap was promptly removed and quickly solidifiedbycooling. The main mass of soap. washeated to. 435. F. under sufficientpressure to prevent steam formation,...and ,was

then quickly released intoa flash dryingehamher. A sample ofthe flashdrieclsoap, which had now lost between.- onethird and one. halfbf itslarly processed, exceptithat3ebenzyl-4emethyl-7- hydroxycoumarin.wassubstituted in place .of the corresponding .unsta'ble derivative.used .in. .(a) ..and the amount .of fluorescer...used .this.,.time

was 0.003%.

(0) Another lot of the same soapwassimilarly processed, exceptthat thistime 0.01%..01. 3-isopropyl-4-methyl-7 -hydroxycoum.arin, wasused as thefluorescer.

(d)- Another lot .of thesame soap, was similarly processed, except thatto .itv no. fluorescing-compound was added.

Examination and testing of the samples from these four lots of soapshowed the following:

6 form, containing about 0.01% of the coumarin derivative, has anenhanced whiteness in day- Fluorescer used 4-OH:-70H coumarin3-benzyl-4-CHa-7-OH coumarin 3-isopropyl-4 cHi-7-OH coumarin NoneAppearance of fresh samples: (1) Before flash drying In daylight Whiterthan (d) In ultra-violet light Fairly strong bluish fluorescence. (2)After flash drying- In daylight Pink discoloration In untra-violet lightFaint fluorescence Appearance of aged samples:

(1) Before flash drying (2) After flash drying Much of whiteness andfluorescence gone.

Discolored and nearly all fluorescence gone.

Whiter than (d) Strong greenish-white iiuo rescence.

Whiter than (d) r. Strong bluish-white fluorescence.

No discoloration. Still whiter than (d). Verylittle loss offluorescence.

Much whiter than ((1) Strong bluish-white fluorescence.

Whiter than ((1) Strong bluish-white fluorescence.

Yellowish cast. No fluorescence.

Yellowish cast. N o fluorescence.

No discoloration. Slightly No appreciable whiter than (d). Some losschange. of fluorescence.

The aging referred to in the above table comprised holding the samplefor 7 hours at 80 F. under strong ultraviolet light, this beingequivalent to about 2 days exposure to summer sunlight.

Example 2 0.10% by weight of 3-isopropyl-4-methyl-7- hydroxycoumarin wasincorporated, as a solution in a perfume made of a. mixture of essentialoils, in a molten well mixed mass consisting of 70 parts of laundrykettle soap and parts of aqueous sodium silicate solution. This mixturewas heated (under pressure) to about 180-225 F. and forced throughatomizing nozzles into the upper portion of a spray drying tower whereit encountered a stream of gases having a temperature of about 300 F.The resulting laundry soap granules were very noticeably whiter than acorresponding product containing no added fiuorescing material, and thisimprovement in whiteness was retained undiminished during a prolongedperiod of storage under summer warehouse temperature conditions.

Example 3 0.01% by weight of 3-benzyl-4-methyl-7-hydroxycoumarin wasincorporated, as a solution in alcohol, in a molten white kettle soap towhich was also added minor proportions of perfume and preservative. Themass was introduced into the hopper of a water cooled soap roll, uponthe surface of which a film of the soap was converted to plasticcondition. This film was cut into ribbons, which were peeled off thecooling roll and fed into a soap flake drying chamber. The resultingsoap flakes or chips appeared decidedly whiter in daylight than similarsoap flakes containing no blue fluorescing material. This improvement inwhiteness persisted indefinitely.

Example 4 As another example, to a 10,000 pound batch of a liquid slurrycontaining 4160 pounds of water, 1160 pounds of a mixture of sodiumsalts of sulfated higher alcohols derived from coconut oil and sodiumsalts of sulfonated alkyl benzene (the alkyl groups being predominantlytetrapropylene), 990 pounds of sodium sulfate, 3240 pounds of sodiumtripolyphosphate, and 450 pounds of miscellaneous minor ingredients, isadded while agitating the batch 0.007% of 3 benzyl 4 methyl '7hydroxycoumarin. The slurry, heated to about 160 F., is pumped toatomizing nozzles at the top of a spray drying tower through whichheated air was circulated. The resulting detergent composition ingranular .light which persisted indefinitely under normal conditions ofstorage, shipment, and use.

In the above examples one may satisfactorily replace the 3-benzyl-, orthe 3-isopropyl-4- methyl-7-hydroxycoumarin with any other coumarinderivative having the aforementioned general structural formula.Frequently one may wish to adjust, within the broad limits mentioned inthe following paragraph, the percentage used so as to make allowance fordifferences in the fluorescence intensities of the different compounds.Some of these are weaker and some are stronger than the intensities ofthe particular compounds used in the foregoing examples. A diethylaminogroup in the 7 position, for example, has in some cases been found toimpart greatly increased intensity of fluorescence in the blue region,as compared to an hydroxyl group in this position. On the other hand,the substitution of NH2 in place of OH in the' 7 position has been foundto decrease slightly the fluorescent intensity of some compounds. Inaddition to variations in intensity, slight differences in the hue ofthe fluorescent radiation are caused by changes in the structure of themolecule.

In general, the amount of alkali-stable blue fluorescing coumarinderivative which may most advantageously be incorporated in detergentcompositions lies between about 0.0005% and 0.25% by weight, dependingon such factors as the natural color and physical form of the untreateddetergent composition, the nature of its processing, the fluorescentintensity and hue of the brightening agent used, and the amount ofwhitening or brightening desired. Under conditions most frequentlyencountered the amount of brightening agent used will be between about0.001% and 0.10% of the weight of the detergent.

Methods of synthesizing the alkali-stable coumarin derivatives used inthe invention may follow known practice. 3-benzyl-4-methyl-7-hydroxycoumarin, for example, may be prepared by a Von Pechmanncondensation (Berichte 16, 2122 (1883)) of resorcinol andalpha-benzylacetoacetic ester. We have prepared this coumarin derivativeby gradually adding a mole of alpha-benzylacetoacetic ester to asolution of one mole of resorcinol in sulfuric acid, cooled in an icebath. After standing overnight, the reaction mixture was drowned in iceand water. The filtered precipitate was recrystallized twice fromalcohol, dissolved in sodium hydroxide and reprecipitated with powderedDry Ice, and recrystallized twice from alcohol with charcoaling. Theproduct melted at 226.3-227.0 Q,

'l'he'ultraviolet absorption maximum for this compound was found tooccur at 326 millimicrons.

Similarly, 3-isopropyl-4-methyl-7-hydroxycoumarin may be prepared bycondensing resorcinol and alpha-isopropylacetoacetic ester, giving aproduct melting at 223.8-225.0 C.

The ultraviolet absorption maximum for this compound was found to occurat 323 millimicrons.

When a 7-hydroxycoumarin having no substituent in the 4 position isdesired resorcinol may be condensed with an appropriate malic acidderivative or with the appropriate derivative of ethyl formylacetate.For example, the 3- methy1-7-hydroxycoumarin may be formed bycondensation of resorcinol and ethyl a1phaformylpropionate (Michael,Ber. 38, 2099) and 3-ethyl-7-hydroxycoumarin by condensation ofresorcinol and ethylmalic acid (Fichter and Goldhaber, Ber. 37, 2382).

When an amino group is desired in the 7 position of a i-methyl coumarinderivative, the ap propriate meta amino phenol is reacted with theappropriate acetoacetic ester. For example, 3-ethyl--methyl-7-dimethylaminocoumarin may be prepared by condensation ofm-dimethylaminophenol and alpha-ethyl acetoacetie ester (Von Pechmannand Schaal, Ber. 32, 3695).

Having thus described our invention, what we claim and desire'to secureby Letters Patent 11s: 1. -A solid form detergent composition :ofalkaline nature having an enhanced whiteness in sunlight, comprisingessentially an alkaline detergent selected from the group consisting of(a) water soluble alkali metal salts of higher fatty acids, and (b)non-soap anionic synthetic organic detergents; and, in a proportion offrom about 0.0005% by weight to about 0.25% by Weight, coumarinderivative having the structural formula R Q I HO O O in-which R is aradical of the group consisting of alkyl and aralkyl, said radicalhaving a saturated carbon atom adjacent to the coumarinring andcontaining no more than 15 carbon atoms, and R" is a member of the groupconsisting of hydrogen and'alkyl of not more than 6 carbon atoms.

2. The product of claim 1 in which the coumarin derivative is3-benzyl-4-methyl-7-hydroxycoumarin.

3. The product of claim 1 in which the coumarin derivative is3-isopropy1-4-methyl-7-hydroxycoumarin.

4. The product of claim 1 in which the detergent ingredient is sodiumsoap. I

CHARLES E. WHEELOCK. WILLIAM B. REYNOLDS.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 7 2,610,152 Ackermann Sept. 9, 1952 FOREIGN PATENTS NumberCountry Date 522,672 Great Britain June 24, 1940 567,716 Great BritainFeb. 28, 1945 731,558 Germany Feb. 11, 1943

1. A SOLID FORM DETERGENT COMPOSITION OF ALKALINE NATURE HAVING ANENHANCED WHITENESS IN SUNLIGHT, COMPRISING ESSENTIALLY AN ALKALINEDETERGENT SELECTED FROM THE GROUP CONSISTING OF (A) WATER SOLUBLE ALKALIMETAL SALTS OF HIGHER FATTY ACIDS, AND (B) NON-SOAP ANIONIC SYNTHETICORGANIC DETERGENTS; AND, IN A PROPORTION OF FROM ABOUT 0.0005% BY WEIGHTTO ABOUT 0.25% BY WEIGHT, COUMARIN DERIVATIVE HAVING THE STRUCTURALFORMULA